1. Field of the Invention
The invention is directed to a method and apparatus for winding a material web.
2. Discussion of Background Information
The present invention relates to an apparatus and method for winding a material web, such as, but not limited to, a paper or cardboard web, onto a reel, in which the material web is guided around a carrying drum, and in which a nip is formed between the carrying drum and the reel. The carrying drum and a winding roll that is being produced (e.g., the reel with the material web wound thereon) are kept in contact with each other during the winding process.
A winding machine and a process for winding a material web is disclosed, for example, in EP 0 483 092 A1. Such winding machines are used, for example, at the end of an operation for producing (or refining) a material web, such as, for example, a paper web. However, such machines can also be used, for example, to rewind a winding roll that has already been completely wound.
During a winding operation, irregularities can occur in cross direction profiles. In particular, irregularities can occur in the thickness profile of a material web. With regard to a paper machine, these irregularities usually occur only temporarily, because such irregularities can be eliminated by, for example, adjusting the head box. Nevertheless, such prior art devices have a disadvantageous influence on the winding formation. For example, a situation can arise in which a winding diameter is greater than a desired diameter at one point of the web width. When his occurs, there is no longer a cylindrical winding formation. An undesirable over-stretching of the material web may then occur, which can, for example, have an adverse effect on the flatness of, for example, graphic paper.
PCT patent document WO 95/30049 and German patent document DE 297 21 832, respectively, disclose a process for producing a fibrous material web, such as, for example, a paper or cardboard web, out of a fibrous suspension, in which the material web, after completely drying, is calendered online and subsequently wound onto a winding roll, However, defects in calender stack rolls, due to, for example, wear or the like, and/or variations in a moisture cross direction profile lead to local thickness variations in the calendering. If the varying thicknesses always occur at the same point in the winding of the web, web stretching and a poor travel of the material web in the reel cutting machine results.